how far must he mirror mz of the michelson interferometer be moved so that 1600 fringes of laser light move across a line int he field of view

The question is not complete. Let me explain Michelson interferometer and how to calculate a question like this.

Answer 4.85 * m

Explanation:

The Michelson Interferometer is an instrument which produces interference fringes by splitting a light beam into two parts, it then recombines them after they have travelled different optical paths.

The formula to measure the minute displacement is Δd=m * λ/2

where m is the number of fringes passing a given point as the movable plane mirror is moved

and λ is the monochromatic lamp of wavelength

In the question, m = 1600. Let us assume that the wavelength is 606 nm

Solution

Δd=m * λ/2

Δd=1600 * 606nm/2 = 1600 * 303nm = 484800nm

We convert the nm to m (nm / )

4.85 * m

i think its c if i'm wrong